Background: Preterm and low birth weight infants are at increased risk of severe rotavirus gastroenteritis. However, many of the infants are not eligible to receive rotavirus vaccine due to over the age limitation within the NICU. Aims of the study: To elucidate safety and immunogenicity of rotavirus vaccine in the preterm and low birth weight infants hospitalized in NICU.

Methods: This study was designed as the prospective study conducted at the NICU of Fujita Health University hospital. This study was approved by the ethical committee in our university. Premature age-eligible infants (2 months) were enrolled to administer rotavirus vaccine (RV5). Stool samples were serially collected from the vaccinated infants (VI) and unvaccinated infants (UVI) hospitalized in the same “pod” from day 0 to day 8 of post-vaccination. During October 10, 2014 and March 20, 2015, 6 VI and 16 UVI were enrolled in this study. Nursing staffs took care of the infants within the same pod under the standard precaution measures. Total RNA was extracted from 0.01 to 1 g of stool sample by using QIAamp Viral RNA Mini Kit. All stool samples were analyzed by RV5 specific real-time RT-PCR targeting VP6 gene of the vaccine strain.

Results: Total of 189 stool samples (61 samples collected from the 6 VI and 127 samples collected from the 16 UVI) were analyzed in this study. Six VI received with 1st dose of the vaccine demonstrated persistent shedding of rotavirus vaccine genome during 1-8 days after the first dose of RV5.Meanwhile, in the one of the six VI received with 2nd dose of the vaccine, no vaccine genome was detected in the stool samples after 6 days of the 2nd dose of vaccination. In contrast to the VI, no vaccine genome was detected from any of the stool samples collected from the UVI.

Conclusion: This study suggests that RV5 may be safe for administration to the preterm and low birth weight infants in NICU. Immunogenicity of the vaccine in these subjects is now evaluating.